The present invention arises as a result of a long-felt need for an improved suspension system for multi-axle vehicles, such as large motor homes and buses. Because of their weight and high centers of gravity, vehicles of this type tend to lack stability on the highway, are frequently deficient in braking performance and handling compared to other vehicles on the road, and provide less than optimum ride from a comfort standpoint. The present invention in terms of a broad objective seeks to substantially eliminate or dramatically improve upon the above and other known deficiencies of prior art suspension systems for vehicles of the class mentioned.
The prior art contains many teachings on vehicular suspension systems which seek mainly to maintain the vehicle in a level stance under varying conditions of loading and/or braking. The known prior art suspensions for vehicles of the type on which the present invention is employed compensate for changes in vehicle loading by maintaining the chassis frame at a design elevation under all conditions of loading between empty and fully loaded. The prior art suspension systems do not possess the ability to improve dramatically the fore/aft or lateral stability of the vehicle within the range of normal and highway speeds, so that emergency lane changing, braking and like maneuvers can be safely carried out. The present invention possesses the above and other capabilities which are absent in the prior art.
A further and more specific object of the invention is to provide an improved suspension for motor homes, buses and the like in which the provision of a tag axle in association with the drive axle of the vehicle and a fluid-pressure operated spring means constantly divides the total vehicle load between the drive axle and tag axle, maintaining a constant portion of the load on the tag axle at all times and under all variations in static and dynamic loading between an empty vehicle and a fully loaded vehicle. This load dividing capability of the invention forms the basis of the greatly improved handling and stability of the vehicle, more effective braking, greater passenger comfort and avoidance of loss of road traction when the tag axle rolls up onto a curb or other elevated surface resulting in lifting of the vehicle drive or traction wheels.
Other features and advantages of the invention will become apparent to those skilled in the art during the course of the following description.